A higher dose of radiation (74 Gy) does not improve overall survival for non-small cell lung cancer (NSCLC) that has spread to the lymph nodes, compared to the standard radiation dose (60 Gy), according to a new study, according to results presented at the 53rd Annual Meeting of the American Society for Radiation Oncology held October 2-6, 2011, in Miami Beach, Florida.
“Most radiation oncologists and lung cancer specialists are surprised by this finding. Although the optimal radiation dose for lung cancer patients has not been tested in a randomized phase 3 trial for over 30 years, most believed that higher doses of radiation cured more patients with lung cancer,” said study investigator Jeffrey Bradley, MD, a radiation oncologist at the Washington University School of Medicine in St. Louis, Missouri.
The goal of the current phase 3 trial was to find out if high doses of radiation improved survival and also if the chemotherapy drug, cetuximab, increased survival among patients with stage III NSCLC. Investigators randomized 423 patients to different doses of radiation therapy and concurrent chemotherapy of paclitaxel and carboplatin with or without cetuximab. Patients received one of four treatment arms: standard-dose (60 Gy) versus high-dose (74 Gy) radiation therapy and to chemotherapy with or without cetuximab.
Two types of external beam radiation therapy were used during the trial: three-dimensional conformal radiation therapy (3D-CRT), and intensity modulated radiation therapy, (IMRT), a newer, specialized form of 3D-CRT that further limits the radiation dose to the normal tissues.
The researchers found that the patients who received the higher dose of radiation (74 Gy) did not have better survival rates than those receiving the standard dose (60 Gy). Subsequently, the two arms of the trial that used high-dose radiation therapy were closed to patient accrual.
Bradley said the trial provides pivotal evidence that the standard dose of radiation therapy for stage III lung cancer should remain at its existing level of (60 Gy) and doses as high as 74 Gy are not better in curing stage 3 lung cancer. He said it is uncertain why this is the case. The data are still being carefully reviewed.
Bradley noted that these finding are important because this is an area that had not been carefully studied in more than 20 years. He noted that it had been 30 years since radiation dose of 60 Gy was established. However, the techniques of radiation have improved a great deal. “This is the largest study to look at this question and it is a definitive study for stage III lung cancer,” said Bradley.